Biology, Eighth Edition (Raven)

Chapter 14: DNA: The Genetic Material

Telomerase Function

Will chromosomes remain stable of over very long periods of time? Each round of genetic replication followed by mitosis or meiosis requires the replication of a complete version of each chromosome. Any accidental changes in chromosome structure will be permanent. These changes will be passed on through future rounds of DNA replication. Therefore any loss of DNA is a serious problem. If the end of a DNA strand is not copied each time the DNA is replicated then the chromosome will shrink continuously as the cell cycle continues. Because errors persist and accumulate over time it is very important to prevent the accumulation of DNA damage and loss.

View the animation below, then complete the quiz to test your knowledge of the concept.


DNA polymerases cannot replicate
A)the 5’ end of circular chromosomes.
B)the 3’ end of circular chromosomes.
C)the 5’ end of linear chromosomes.
D)the 3’ end of linear chromosomes.
E)both the 5’ and 3’ ends of linear chromosomes.

Telomerase is unique because it contains
A)a DNA molecule.
B)an RNA molecule.
C)different RNA molecules.
D)different DNA molecules.
E)both DNA and RNA molecules.

Which of the following best describes the function of telomerase at the telomere?
A)It makes special primers that do not need to be removed.
B)It synthesizes new DNA without the use of a template.
C)It adds new DNA to both strands of the telomere overhang.
D)It adds new DNA to the shorter strand of the telomere overhang.
E)It adds new DNA to the longer strand of the telomere overhang.

Telomeres consist of direct repeat sequences.

In the absence of telomerase activity, chromosomes are shortened slightly after every round of replication.
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